1. Field of the Invention
The present invention relates to the removal and/or recovery of the fluorinated surfactant APFO from water, in particular from drinking or waste water that is contaminated with APFO.
2. Description of the Related Art
Current technology for the removal of APFO from contaminated drinking water utilizes granular activated carbon (GAC). Current technology for the removal of APFO from waste water utilizes either granular activated carbon or ion exchange resins. However, current technology is not 100% efficient at removing extremely low concentrations of APFO. According to page 35 of the February 2006 Report to the Senate Environment Committee titled, “INVESTIGATION OF PERFLUOROCHEMICAL (PFC) CONTAMINATION IN MINNESOTA, PHASE ONE, by Fardin Oliaei, Ph.D., Former Emerging Contaminants Program Coordinator, Don Kriens, M. S., P. E., Principal Engineer, and Katrina Kessler, M. S., Staff Engineer, the activated carbon systems installed for the Cottage Grove, Minn. plant site were only 46% efficient for the removal of APFO.
GAC filters installed in the Mid-Ohio Valley by the DuPont Company in partial settlement of the APFO-contamination class-action lawsuit were expected to have a five-year replacement life, but saturated in less than four months. The use of electrosorption for the removal and recovery of APFO is a new, inexpensive and efficient technique for purification of either drinking or wastewater contaminated with APFO. Felix, et.al. (U.S. Pat. No. 6,613,941) in his development of a method for recovering parts per million of fluorinated alkanoic acids from waste waters, utilized adsorption to an anion-exchange resin as the basis for the removal and recovery process and included electrocoagulation to precipitate colloids interfering with the anion exchange resin. While moderately effective at parts per million concentration levels, these techniques are ineffective at removing the extremely low levels of APFO currently found in drinking water.